Smooth, mobile polyvinyl chloride coating compositions



storage.

Patented May 16, 1950 SMOOTH, MOBILE POLYVINYL CHLORIDE COATINGCOMPOSITIONS Noel Armstrong, Newburgh, N. Y., assignor to E. I. du Pontde Nemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application March 1, 1946, Serial No. 651,389

8 Claims. (Cl. 260-23) This invention relates to new compositions ofmatter and more particularly to vinyl chloride polymer-plasticizerpastes. Specifically, this in vention relates to vinyl chloridepolymer-plasticizer paste containing a volatile diluent mixture.

Vinyl chloride polymers are being used in large amounts in a widevariety of applications. Many of these applications involve the use orthese resins in a plasticized form as coating for textiles, metals, andthe like. In order to apply the resin composition it is often necessaryto dissolve the resin in a volatile solvent which is volatilized afterthe coating is in place. This operation is time consuming in itself, butit also makes necessary the recovery of the volatile solvent which addsto the cost and, in addition, the process often requires an excessivenumber of applications to build up the desired coating thickness due tothe limited solubility of the resin. Although polyvinylchloride-plasticizer pastes containing a high proportion of resin andplasticizer are known, improved coating properties are desirable.

This invention has as its general object the preparation of plasticizedvinyl chloride polymer coating compositions without the use .of highproportions of volatile organic solvents, which contain a highproportion of the film-forming composition showing superior coatingproperties. A specific object is the preparation of plasticized vinylchloride polymer coating compositions which are stable with respect toviscosity after Other objects will appear as the description of theinvention proceeds.

These objects are accomplished by the following invention whichcomprises the preparation of compositions suitable for coatingapplications by mixing finely divided vinyl chloride polymer,plasticizer, and a special diluent mixture which is compatible with theplasticizer and has no solvent action on the resin.

Mobile pastes which show superior coating properties and which containonly low proportions of non-solvent volatile diluents can be prepared bymixing finely powdered polyvinyl chloride resin, plasticizer, and adiluent mixture which is compatible with the plasticizer but has nosolvent action on the resin in an open vessel with stirring or inmechanical mixers well known in the art without the aid of heat andpressure. In order to prepare smooth free flowing pastes, the resin andpigments must be reduced in particle size not over 5 microns in diameterand preferably not over 1.5 microns in diameter. If pigments and fillersare used, it is desirable first to grind a mixture of plasticizer andfiller and/or pigments, then mix this composition with the finelypowdered resin with the aid of low proportions of volatile organicdiluents.

The following specific examples are given by way 01 illustration and notlimitation in which the percentages are by weight:

Example I A polyvinyl chloride paste of the following composition wasprepared:

Per cent Polyvinyl chloride powder 37.8 Butyl acetyl ricinoleate 15.7Tricresyl phosphate 10.2 Blown castor oil 1.1

Pigments:

Bone black, 19.27% CP chrome green dark, 4.67% CP chrome green light,2.55% 35.2

TiO2 on barium base, 5.68% Barytes, 67.83%

The pigments were previously ground in the plasticizers in aconventional manner. The pigment-plasticizer mixture was added to a Wormgear type of mixer and then the polyvinyl chloride powder having anaverage particle size of 2.0 microns in diameter was added to the mixer.The dry powder was mixed with the pigmentplasticizer mixture to obtain aheavy paste, which was too heavy for practical doctor knife coating. Theabove composition was diluted to solids with various ratios of ethylalcohol and V. M. & P. gasoline. The viscosity of the dilutedcompositions was measured with a Stormer vlscosimeter employingrevolutions with a 1000 g. weight.

3 4 The viscosity results initially and after 1 day, ethyl alcohol or V.M. h P. gasoline alone was 2 days. 4 days, 6 days, and 14 days were asfollows: too stiff for doctor knife coating.

fltonnsr Viscosity 100 Revolutions-1,000 g. Weight Arie: -sm 2 AM 4 meman 313 rlefi' day day day days do! Second: Seconds Seconds SecondsSeconds Seconds no n as an we too no no too no so so no one 2&1 m an no7 so so no. no m -2l8 m so so so 100 is: no 185 me so 10 4a no 10s 24:an no as Is as no me see m 350 is as 140 an no 135 no as! 100 (I) (I)(I) 1 Tee heavy to determine Prom the above table it is noted that aExample In dilution of the heavy paste with various mixtures of ethylalcohol and V. M. 8: P. gasoline result in lower viscosities, bothinitially and after aging, than when either the ethyl alcohol or V. M.I: P. gasoline is used alone as the diluent.

Example I! The undiluted heavy paste, described in Example I was alsodiluted with 10% of the same diluent mixtures as described above, and 2%of a surface active agent, e. g., one of the petroleum Polyvinylchloride pastes of the following com- To this heavy paste sufficientvolatile diluent was added until the solids content was between 80%hydrocarbon sodium sulfonates such as alkanol 95 and 90%. When sodiluted the ratio of resin WXN based on the resin was also added and toplasticizer may vary between parts of resin the following viscosityresults were obtained: to 50 parts of plasticizer, and 10 parts of resinpresenting Ste Viscoei i i bvlfimpoeition 10o Revolutfirfe-LOM 2mm" Al VM kl arm-1 Afters Aiteri is. Aim-14 ill basoline day days days days daysFormula 1 Seconds Swami: Seconds Seconds Seconds Second: we so 170 260no see no so so so as so 10 02 so I so 11 2s 31 42 4e 40 so so 14 1o 22so :42 a4 40 no 14 11 21 as 21 so so 10 1s 11 22 so so 4 as in so 15 soa as a4 a7 loo 2: :2 40 co to 108 on the weight of the The use of awetting agent to facilitate the formation of mobile pastes is disclosedand claimed in copending application S. N. 675,309, filed June 7, 1946.

, It is apparent that there is a definite advantage with respect toreduced viscosity and stability by the use of various mixtures of ethylalcohol and V. M. I P. gasoline in the cases where a wetting agent isused as well as in cases where such wetting agents are not used. From apractical viewpoint in the case of the paste containing 10% of a diluentmixture of 40 parts ethyl alcohol and parts V. M. k P. gasoline and nosurface active agent, an increase in viscosity from 49 seconds to 198seconds after 14 days as measured by the Stormer viscosimeter isconsidered to be a stable composition for plant coating operations,whereas the same composition diluted with either to 30 parts ofplasticizer. The volatile diluent with which the paste was thinnedcontained about equal parts of ethyl alcohol and V. M. I: P. gasoline.The resulting paste was then spread on a fabric and aftmheating for ashort period was converted into a tough durable coating.

In place of polyvinyl chloride in the examples I and alpha-chloroacrylicacid or methacrylic esters such as the methyl, ethyl or propyl esters.copolymers of vinyl chloride with vinylidene chloride and alsocopolymers of vinyl chloride and vinyl esters of organic acids such asvinyl acetate. These vinyl chloride copolymers and polymers can beprepared by polymerizing monomer or monomer mixtures in aqueousemulsions as is well known in the art. When copolymers are usedpolyvinyl chloride is present in major amount-usually about 95%polyvinyl chloride and of the other component. To obtain the polymer ina suitable form for use in preparing the pastes of this invention, thepolymers may be isolated from the dispersion by coagulation according toconventional methods such as by the addition of a salt solution,filtered and dried or by spray-drying the resin emulsion.

It is essential that the resin be in as finely divided form as possiblein order to obtain mobile pastes and it may thus be necessary tosubdivide I the resin particles further. This may be accomplished by avariety of means known in the art such as ball milling or grinding. Aconvenient method to reduce the particle size of the resin consists inpassing it through a Micronizer or Mikroatomizer which subjects theresin particle to a high velocity rotating motion in a confined chamberthat causes the agglomerates to subdivide. It is particularly desirablethat the resin particles have an average diameter of less than 2 micronsas determined by the Fischer Sub Sieve Sizer (Goodan E. L. Smith, C. M.Ind. Eng. Chem. Analy. Ed. 12, 479-482 (1940)). However, for certainuses, such as cable lacquers where extremely smooth coatings are notrequired, larger resin particles, up to 5 microns average diameter, canbe used.

It will be apparent from the above that the greatest advantages of thepresent invention will be obtained when Irom to 75% alcohol and from 85%to 25% Y, M. 8: P. naphtha is used to make up the diluent. The terms V.M. & P. gasoline and V. M. 8: P. naphtha" are used synonymously in thisapplication.

The liquid plasticizers that may be used in preparing the compositionsof this invention include those high-boiling compatible materials whichare poor solvents for the resin at room temperature but are solvent atelevated temperature. Plastici'zers among others that may be usedinclude tricresyl phosphate, di(butoxyethyl) phthalate, dibutylphthalate, methoxyethyl acetyl ricinoleate, sebacic acid esters such asdi(butoxyethyl) sebacate and combinations thereof or any high-boilingcompatible plasticizer which is a poor solvent for the polymer at lowtemperatures but is a solvent at elevated temperatures. The proportionof liquid plasticizer that may be used in preparing the mobile pastes ofthis invention is dependent to a large degree on the proportion of otheragents such as pigment and filler present in the final composition. Ingeneral, mobile pastes may be prepared from resin and plasticlzermixtures containing from 35 to by weight of the plasticiZer based on theweight of resin and plasticizer.

The pigments and fillers may be omitted to make colorless films andcoatings if desired.

It is apparent that many widely difierent embodiments of this inventionmay be made without departing from the spirit and scope thereof, andtherefore, it is not intended to be limited except as indicated in theappended claims.

I claim:

1. The composition 0; claim 0 in which a wetting agent is present.

2. The composition of claim 8 in which the particle size of the polymeris below 5 microns.

3. The composition of claim 8 in which the average particle size of thepolymer diameter is less than 1.5 microns.

4. The composition of claim 8 in which the polymer is polyvinylchloride.

5. The composition of claim 8 in which the polymer is a copolymer ofvinyl chloride and diethyl fumarate.

6. The composition of claim 8 in which the polymer is a copolymer ofvinyl chloride and vinyl acetate.

7. The composition of claim 8 which has approximately the followingcomposition by weight:

Per cent Polyvinyl chloride powder 312$ Butyl acetyl ricinoleate 15.7Tricresyl phosphate 10.2 Blowncastor oil 1.1 Pigment 35.2

the said composition being dispersed in a mixture consisting of 40%ethyl alcohol and 60% V. M. 8: P. naphtha in amount sufficient tocontain solids and 10% diluent by weight.

8. A coating composition having a smooth, mobile and relatively stableconsistency which comprises a finely divided polymer selected from thegroup consisting of homopolymers of vinyl chloride and copolymersthereof obtained b polymerizing at least of vinyl chloride and up to 5%of a monomer copolymerizable therewith, from 35% to 80% by weight of aliquid plasticizer which is a solvent for the polymer at high but notlow temperatures, and from about 10% to 20% by weight based on the totalcomposition of a diluent consisting of 15% to 75% of ethyl alco= hol and85% to 25% of V. M. 8: P. naphtha by weight, the percentage ofplasticizer being based on the combined weight of plasticizer andpolymer.

NOEL ARMSTRONG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Jenkins June 26, 1946

8. A COATING COMPOSITION HAVING A SMOOTH, MOBILE AND RELATIVELY STABLECONSISTENCY WHICH COMPRISES A FINELY DIVIDED POLYMER SELECTED FROM THEGROUP CONSISTING OF HOMOPOLYMERS OF VINYL CHLORIDE AND COPOLYMERSTHEREOF OBTAINED BY POLYMERIZING AT LEAST 95% OF VINYL CHLORIDE AND UPTO 5% OF A MONOMER COPOLYMERIZABLE THEREWITH, FROM 35% TO 80% BY WEIGHTOF A LIQUID PLASTICIZER WHICH IS A SOLVENT FOR THE POLYMER AT HIGH BUTNOT LOW TEMPERATURES, AND FROM ABOUT 10% TO 20% BY WEIGHT BASED ON THETOTAL COMPOSITION OF A DILUENT CONSISTING OF 15% TO 75% OF ETHYL ALCOHOLAND 85% TO 25% OF V. M. & P. NAPTHIA BY WEIGHT, THE PERCENTAGE OFPLASTICIZER BEING BASED ON THE COMBINED WEIGHT OF PLASTICIZER ANDPOLYMER.